Piston



PISTON F. M. MOORE.

Filed Feb. 18, 1929 Oct. 29, 1929.

INVENTOR FMMoore Qfi mil-t,

ATTORNEY Fig? Patented 0a. 29, 1929 V UNITED STATES FRED M. MooRnor OAKLAND, CALIFORNIA, AssIGNoRro ECONOMY on. SLOT PISTON COMPANY, or RENO, NEVADA, ACORPORATION or NEVADA rrsron.

Application filed February 18,

over the structureshown in my pending application for patent, Serial No. 320,592 filed November th, 1928. a c

The principal object of the present invention is to provide a piston constructed to attain the same ends as was the case with the previous one, namely to prevent what is commonly known as oil pumping; but which is so arranged that such pumping is more positively prevented than was previously the case.

A further object of the invention is to produce a simple and inexpensive device and yet one which will be exceedingly ei'i'ective for the purpose for which it is designed.

These objects I'accomplish by means of such structure and relative arrangement of parts as will fullyappear by a perusal of the following specification and claims.

In the drawings similar characters of reference indicate corresponding parts in the several views: I

Fig. 1 is a fragmentary sectional elevation of a gas engine piston, associated with the necessary compression rings showing the piston on its downor suction stroke. I

Fig. 2 is a similar view showing the piston on its upward or compression stroke.

Fig. 3 is a fragmentary sectional plan taken on the line 3-3 of Fig. 2

Referring now more particularly to the characters of reference on the drawings, the

. numeral 1 denotes the upper body portion of the piston in which the usual annular ring grooves 2 are cut, the skirt 8 below the upper portion and which has the wrist pin bearings 4 therein having air passages 5 of some sort out through just (below the lowermost ring groove. This construction is standard in one form or another in almost all modern gas engine pistons and prevents the formation of a vacuum seal between the bottom of the skirt andthe ring grooves.

A small continuous annular groove 6 is cut in the land between the lowermost ring grooves, slots 7 being cut through from the interior of the piston at intervals to communicate with said groove. From the bottom of Ys' ri N 34 3 5, 1

eachsuch slot intermediate its inner and outer ei'ids'i'a'smallbypass 8 connects with the top of the lowest ringgroove2 adjacent the backl' thcreof,"said bypass being: drilled so as to have an outward slant from the slot to the groove.v "Somewhat larger openings 9 are drilled from the back of said lowest ring groove at the bottom straight through to the interior of the piston.

The theory of operation and function of v the above features of construction is as followszl" l i I Onthe downward movement of the piston during the suction stroke the pressure in the cylinder above the piston is considerably less than that in the interior of the piston, as

willbe evident; the latter pressure being substantially atmospheric. The compression rings :10 which frictionally engage the cylinder "walls .are 'relative ly retarded in their downward movement and their upper faces are consequently. tightly engaged with the upper facesof the grooves, leaving clearance between their lower faces and the bottom of the grooves, as shownin Fig. 1. i I

With the provision of the slots 7 alone how ever, as in the previous construction, on the reat;

dow'n str'oke of the piston um relatively g crank case pressure acts both through the slots 7 to the groove (Sand the upper outer edge A of;the lower ring, andthrough the holes 9 to thelower ring groove and to the lower outer edge B ofsaid ring. i

uoh pressures therefore actagainst any oil in their path (and which has, collected back of and above the lower ring during the previous upstroke) and tend to force the oil upwardly v rather than allowing the same to drain back into the crankcase through the openings 9, thus defeatin'g'the object it is desired to attam. I v

On the upward'stroke of the piston, how everfall oil collecting between the cylinder wall and groove 6, and back of the lower ring, will drain back to the interior of the piston by gravity provided the vacuum back of this oil is released or broken. I a

"During this stroke, the setting of the rings is reversed from that previously'set forth and the rings are clearof the tops of their grooves and sealed against the bottom of the same, as shown in Fig. 2. To give this desired relief for the oil, the bypasses 8 are provided. These allow the vacuum pressure otherwise 5 holding the oil sealed back of the lower ring to be broken -byallowing the passage of air through the slots 7 and bypasses 8 to the top of the lower ring-groove, enabling theoil to flow by gravity both from behind the ring 10 and from the groove Garids'lots .IZ, back into the interior of the piston.

The slots 7 are therefore drained of their oil with each upward movement .of the piston sothat they are always clear on the down stroke of the piston, thus providingthenecessary vacuum break just above. the lower ring and positively preventing oil pumping.

It will be of course understood that" the clearance between the ,rings and grooves 2e shown in the drawings has been exaggerated for the purposes of "illustration. It is well known howeverthat such clearance, no Ina-tter how small, inevitably exists and as such clearance increases with the age and wear of -the motorthe necessity for the non-pumping arrangement becomes of course greater.

From the foregoing description it will be readily seen that I have produced such a de- 7 in vice as substantially fulfills the objects of the invention as set forth therein.

While this specification-sets forth in detail thepresent and preferred construction of the device, still'in practice such deviations from such detail may be resorted to as do not form 'a departure from the spirit of theinvention,

as defined by the appended claims.

Having thus described my invention what I claim as new and useful and desire to secure by Letters Patent is:

40* 1. A piston comprisinga hollow body having spaced annular ring-grooves,an additional annular groove in the outer face of the land between adjacent. ringegrooves, .pase sages from said additional groove to the interior of the piston, and oil passage means from said passages intermediate their ends to the interior of the piston at a lower level therein, said passage means including the space between'the back of the lower ring groove and the ring therein.

2. A piston comprising a hollow body having spaced annular ring-grooves, an additional annular groove in the outer face of the land between adjacent ring-grooves, slots cut through from theinterior of the piston and communicating with said additional groove, a bypass from each slot intermediate its ends to the top of the ring groove below; I said ring groove having spaced openings 5 fronitheback thereof to the interior of the piston. I

In testimony whereof I affiix my signature.

FRED Moor n 

